Finding the Answer: Techniques for Locating Students' Answers in Handwritten Problem Solutions

In many academic subjects, especially science, engineering, and math, paper-based problem solving is an important part of education. However, grading such work can be prohibitively expensive in large university courses. As a remedy, we have developed techniques to support the automated grading of handwritten problem solutions. Students complete their work using Livescribe digital pens and draw boxes around the final answers. We developed techniques that identify the answers by locating the boxes. This problem is challenging as the written work contains a mixture of diagrams and equations, and boxes frequently appear as a part of the diagrams. Additionally, the boxes must be segmented from the remainder of the writing. Thus, a simple shape recognizer is inadequate for this task. Our techniques efficiently locate answer boxes within a complex page of free-form writing. Furthermore, our techniques are designed to be robust to the wide range of variations in the way students write. In a test on 2022 pages of homework problems, our techniques correctly located 95.3% of the 4473 answer boxes. These techniques are an important step towards automated grading of handwritten work because once the answer boxes are located, a variety of handwriting recognition methods can be used to interpret the answers.